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an investigation of dual stator winding induction machines

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The reactive power c<strong>an</strong> either be provided by the power system when it is connected<br />

to the grid or by capacitors when it is working as isolated generating system. The<br />

capacit<strong>an</strong>ce requirement is so import<strong>an</strong>t that much work has been done on this area. In<br />

[8.4], a comparative study <strong>of</strong> steady state perform<strong>an</strong>ce <strong>of</strong> both long-shunt <strong>an</strong>d short-shunt<br />

configuration <strong>of</strong> SEIG under various loads was presented. The <strong>an</strong>alyzed results show that<br />

the short-shunt connection has better voltage regulation under higher load voltages while<br />

long-shunt connection will be better under low load voltages. A methodology has been<br />

explained to choose appropriate set <strong>of</strong> values <strong>of</strong> capacitors for desired voltage regulation<br />

in [8.5]. Only the pure resistive load was used in the <strong>an</strong>alysis <strong>an</strong>d studies, although the<br />

effectiveness <strong>of</strong> the proposed methodology under reactive load has been claimed by the<br />

authors. A formula for determining minimum self-excited capacitor requirement for<br />

<strong>induction</strong> generators is also presented in [8.6]. A minimum air gap flux linkage that is<br />

required for the self-excitation <strong>an</strong>d stable operation <strong>of</strong> <strong>an</strong>d SEIG feeding <strong>an</strong> imped<strong>an</strong>ce<br />

load has also been studied in [8.7]. The perform<strong>an</strong>ce <strong>of</strong> a self-excited <strong>induction</strong> generator<br />

is <strong>an</strong>other interesting topic since the perform<strong>an</strong>ce <strong>an</strong>d operating limitations <strong>of</strong> this kind <strong>of</strong><br />

machine depend on the output voltage, frequency, rotor speed, load condition <strong>an</strong>d<br />

terminal capacit<strong>an</strong>ces. An <strong>an</strong>alytic method for steady state <strong>an</strong>alysis <strong>of</strong> this machine was<br />

reported in [8.8]. The perform<strong>an</strong>ce <strong>of</strong> a self-excited <strong>induction</strong> generator under a wide<br />

r<strong>an</strong>ge <strong>of</strong> varying conditions has also been studied in [8.9-8.10]. The use <strong>of</strong> damping<br />

resistors across series capacitors is proposed to damp out the starting tr<strong>an</strong>sients <strong>an</strong>d for<br />

the stable operation in [8.11]. The perform<strong>an</strong>ce improvement <strong>of</strong> self-excited <strong>induction</strong><br />

generators from the machine parameters <strong>an</strong>d machine design view points c<strong>an</strong> be found in<br />

[8.12, 8.13]. The stability <strong>an</strong>alysis <strong>of</strong> self-excited <strong>induction</strong> generators has been reported<br />

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